No longer require LD_LIBRARY_PATH to be set (XCC)

Previously we had to have LD_LIBRARY_PATH =/lib set in the environment
for all binaries to be able to find their shared libraries.  This was
because we had the wrong set of default paths specified in our ld.so
dynamic loader library.  This patch fixes that.

I had to manually set the variable "default-rpath" in
glibc-2.14.1/Makeconfig to make this work.  By default this value is set
to the lib path in our cross compiler (i.e.
x86_64-ros-gcc/x86_64-ros/lib/).  This default path is sufficient if you
only ever use the resulting ld.so file on the host machine.  The problem
is, we manually copy this file over to run natively on akaros, and at
this point, the default-rpath that got set is bogus.  There's really no
way around it, but to manually set it because of the weird way we are
moving this library around.

Anyway, we no longer have to have an LD_LIBRARY_PATH set for every
executable, ld.so knows to look in /lib by default.